Material comprising a diazomum com-



United States Patent ONE-COMPONENT DIAZOTYPE PROQESS AND MATERIALCOMRRHSING A. DIAZONIIM COM- POUND AND AN ()RTHOPHOSPHATE JohannesHem-ions Andreas Wilder's and Peter Johannes Nieoiaas van denKroonenherg, Venlo, Netherlands, assignors to Chernische Fahriek L. vander Grinten N.V., Venlo, Netherlands, a corporation of the NetherlandsNo Drawing. Filed Nov. 10, 1959, Ser. No. 851,948 Claims priority,application Netheriands Nov. 10, 1958 6 Claims. (Cl. 96-49) Theinvention relates to one-component diazotype material and moreparticularly to such material in which the light-sensitive layer has anacid reaction and contains a p-amino benzene diazo compound which has agreater coupling activity than p-diazo ethyl benzylaniline, which isderived from a tertiary amine with only one aryl radical attacheddirectly to the tertiary nitrogen atom, and which carries in the4-position the diazo group, in the 2-position an alkoxy, aralkoxy oraryloxy group, and in the 5-position a hydrogen atom, a halogen atom, amethyl group or an alkoxy group.

Several of these diazo compounds are known. They are very sensitive tothe light of the mercury vapour lamps commonly used in the moderndiazotype process. Compounds in which the substituent in the 2-positionis an alkoxy group are known, for example, from the Belgian Patent No.564,343. Diazotype material sensitized with such a diazo compound isextremely suitable for the visual observation of the endpoint of theexposure when copies are made in the light of actinically fluorescentmercury vapour lamps.

Many diazo compounds of the type described above couple more activelythan p-diazo ethyl benzylaniline. Their coupling activity, in comparisonwith that of p-diazo ethyl benzylaniline, can be determined in vitro bymeasuring the time in which a given proportion for instance) of thediazo compound to be examined will have coupled in a given molarconcentration (0.1 milli-' molar, for instance) with the couplingcomponent 1- phenyl 3-methyl-5-pyrazolone in a given molar concentration(1.0 millimolar, for instance) in a buffer mixture of a givencomposition and a given pH at a given temperature.

The compounds coupling more actively than p-diazo ethyl benzylanilineare very suitable for the manufacture of one-component diazotypematerial which can be developed according to the so-called semi-Wetprocess.

In the diazotype process with semi-wet development, imagewise exposedone-cornponent diazotype material is developed by spreading a thin layer(a layer of 8 g. square meter for instance) of developing liquid,containing one or more azo components and one or more buffer salts,evenly over the surface of the diazotype material. This can be donemechanically, e.g. with the aid of developing apparatus as described inthe Dutch Patents Nos. 53,196 and 55,162.

The development always has to be complete, i.e. all of the diazocompound left on the diazotype material after the imagewise exposure hasto be converted completely into azo dyestuif, despite the differenttemperatures occurring in practice, which vary, for example, from 10 to30 C., and the diiferent humidities of the air ocurring in practice,which affect the drying speed of the layer of developing liquid appliedon the diazotype material.

Preferably the azo dyestuffs formed should have the same colour evenunder the said varying conditions.

In semi-wet development under the said varying conditions good resultscan be achieved with the abovementioned one-component diazotype materialby adaptation of the composition and the pH of the developing liquid tothe composition of the light-sensitive layer, and to the reactivity ofthe diazo compound used and of the azo component used.

Good results can thus be obtained with alkaline phloroglucinoldevelopers of a pH between 8.5 and 10.5 which have been bufferedsufliciently. They yield browncoloured azo-dyestuffs in the semi-wetdevelopment of one-component diazotype materials which have beenmanufactured with diazo compounds according to the above definition andthe light-sensitive layer of which has the composition that is usual forone-component diazotype materials, containing inter alia a smallquantity of acid, such as citric aid, tartaric acid or alum. The desiredpH value and the desired bufl'er capacity of the phloroglucinoldevelopers in question are achieved with the aid of buifer salts such ascarbonates, borates, citrates, phosphates, tartrates, and the like. Theborate developers described in the United States Patents Nos. 2,657,137and 2,657,141 are especially suitable.

Phloroglucinol developers showing a stronger or weaker alkaline reactionthan those with pH between 8.5 and 10.5 are less suitable, the firstbecause they have poor keeping qualities owing to oxidation uponexposure to the air, the latter because they often fail to bring about acomplete conversion of the diazo compound into azo dyestutf in thesemi-wet development of diazotype material manufactured wtih diazocompounds according to the above definition and with a light-sensitivelayer of normal composition.

In the diazotype process with semi-wet development phloroglucinol is theazo component most widely used. This compound can form mono-, bisandtris-azo dyestuffs which are of different colours. The colours of thetrisazo dyestuffs are darkest and those of the mono-azo dyestuffslightest. As in practice a large visible image contrast in the developeddiazotype copies is often desirable and the image contrast in general islarger according as the colour of the azo dyestuff formed duringdevelopment is darker, the formation of as dark as possible an azodyestufi is often desirable.

If larger than normal quantities of the acids or acid salts commonlyused in diazotype materials, such as tartaric acid, citric acid,aluminium sulphate, and the like, are applied in the light-sensitivelayers of one-component diazotype materials with diazo compoundsaccording to the above definition, then, in semi-wet development withthe said alkaline-reacting phloroglucinol developers which have beenadapted to the higher acid content of the lightsensitive layer, dark azodyestuffs, sometimes even dependent on the diazo compound chosen-blackazo dye stuffs, and thus copies with a greater image contrast, can beobtained.

However, owing to small deviations in the concentration of the developerand in the quantity of developer applied on the copy in semi-wetdevelopment, which deviations (hereinafter referred to as developmentfluctuations) often occur in practice, e.g., in consequence ofinaccuracies in the manufacture of the developing liquid, throughevaporation of the latter during use, through irregularities in theoperation of the developing apparatus, e.g., owing to vibrations, and todifierences in developing speed, objectionable deviations in the shadeof the azo dyestufis are apt to appear. These deviations of shade arethe more objectionable as the azo dyestuffs are darker. Especially withblack azo dyestufis such deviations are inconvenient.

7 In the one-component diazotype material according to the presentinvention the acid-reacting light-sensitive layer contains a quantity ofalkali metal and/or ammonium orthophosphates in the amount of thestoichiometric equivalent of at least 0.15 g. and at most 0.9 g. of Pper m? (i.e., per square meter) of said material.

One-component diazotype material according to the invention yields, bysemi-wet development with the said alkaline-reacting phloroglucinoldevelopers, darker azo dyestuifs than corresponding diazotype materialwhich contains no orthophosp'hate but only a larger quantity of one ofthe commonly used acids or acid salts. Moreover, the colours of the azodyestuffs show considerably smaller deviations, or none at all, inconsequence of the said deviations in the concentration and theapplication of the developer.

Quantities of orthophosphate which are the stoichiometric equivalents ofless than 0.15 g. of P 0 per m? are of little utility, because theeffect of the invention is not achieved with them, or not to asuflicient degree. Quantities which are the stoichiometric equivalentsof more than 0.9 g. of P 0 per m? cause difliculties in thesensitization. The spreading of solutions containing such largequantities of phosphate over the surface of the di azotype material isnot suificiently uniform; they penetrate too far into some supports,such as paper.

The desired content of orthophosphate can be obtained by dissolving asuitable quantity of alkali metal or ammonium orthophosphate, e.g.,primary sodium phosphate, in the sensitizing liquid, the magnitude ofthe quantity of sensitizing liquid which in the manufacture of thediazotype material is applied on the support per unit area naturallybeing taken into account.

The desired content of orthophosphate can also be obtained by treatingthe surface of the support to be sensitized, before the sensitization,with a solution of a suitable quantity of phosphate or by subjecting thesensitized surface to an after-treatment with such a solution. Primary,secondary or tertiary orthophosphates or mixtures of them can be used.Further, mixtures of orthophosphoric acid with alkali metal or ammoniumsalts of acids which are weaker than orthophosphoric acid may beemployed. The phosphate-containing light-sensitive layer, however, mustalways show an acid reaction.

It is desirable in the production of diazotype layers to avoid volatileacids or acids with an offensive smell, such as formic acid, aceticacid, propionic acid or butyric acid. Accordingly, when using theabove-mentioned mixtures of orthophosphoric acid with alkali metal orammonium salts of weak acids, the use of salts of such volatile acids oracids with on offensive smell is also avoided.

The pH of the light-sensitive layer, or rather the pH of thelight-sensitive surface (the light-sensitive layer of many diazotypematerials, amongst others diazotype paper, is too thin for pH-determinedinside the layer), is partly dependent on the pH and the acid and/or thebufler content of the support, but especially On the pH and the acidand/or the buffer content of the liquid(s), which is (are) used for themanufacture of the lightsensitive material. By providing for a suitablecomposition of this (these) liquid(s) it can easily be given a certainvalue. In practice this is not chosen below 2, since many diazotypematerials, e.g., diazotype paper, become brittle at such a high degreeof acidity of the light-sensitive layer and the sizing of the paper isadversely affected. It will preferably not be chosen higher than about6.5 because the keeping qualities of the lightsensitive layers are thentoo small. The surface-pH of the light-sensitive layers of the commonone-component diazotype materials in most cases is between 3.5" and 4.5.

In order to improve the keeping qualities of the lightseusitivematerial, a pH below 3.5 is sometimes chosen, particularly when abovethis pH value the keeping qualities would still leave much to be desiredand if the application of stabilizers such asnaphthalene-1.3.6-trisulphonic acid and its salts is not possible, forexample owing to the formation of precipitates in the sensitizingliquids. If, however, stabilizers can be applied, a higher pH, e.g.,between 4.5 and 6.5, may be chosen in many cases. As the pH which thelight-sensitive layer has before the development is to a certain extentalso decisive for the formation of the azo dyestuif, it will have to beadapted somewhat to the coupling activity of the diazo compound used andto the developer to be used. The pH of the light-sensitive layer duringthe development, however, is much more important for the formation ofthe azo dyestuff.

Upon comparison of diazotype material according to the invention withcorresponding diazotype material which contains instead of phosphate alarger quantity of the commonly used acids or acid salts, it thereforehas to be taken into account that it is not necessary for the surface-pHwhich is measured for the comparable diazotype materials before thedevelopment to be exactly the same. The comparability is determined inthe first place by the results of the development, in other words by thequestion of whether in the development the same quantity of diazomolecules is converted into azo dye-stuff in about the same time.

The surface-pH can easily be determined by wetting the ligh-sensitivesurface locally with distilled water with the aid of the so-calledsurface-electrodes of an electric pH- meter that has been adjusted tothe measurement, e.g. the surface glass electrode 613 14/ and thesurface calomel electrode 6B 15/100 of the pH-meter type 6C of N.V.Electrofact, Amsterdam, Holland, in such a way that between the twoelectrodes via the wetted surface an electrical contact is effected, andby subsequently reading the deflection of the meter.

The inclusion of orthophosphate in light-sensitive layers ofone-component diazotype materials employing the diazo compoundsaccording to the above definition is not known.

One-component diazotype material is known in which a diazo film layercontains as diazo compound p.p'-tetrazoo.o'-dianisidine and alsocontains a large quantity of primary sodium phosphate. The phosphateserves to prevent the bleeding of the azo dyestuff duringbath-development, and can therefore be replaced by an equal quantity ofcommon salt. In the semi-wet development of this material with the saidalkaline-reacting phloroglucinol developers no favourable effect of thephosphate with regard to deviations in the shade of the azo dyestuflsowing to deviations in the concentration and the application of thedevelopers is observed.

Another known one-component diazotype paper is that sensitized with theactively coupling 4-diazo-2,5-diethoxy benzoylanilide, thelight-sensitive layer of which contains a small quantity of primarysodium phosphate. This quantity is smaller than that which correspondsto 0.15 g. of P 0 per 111. The paper is suitable for develop ment withan acid, buffered phloroglucinol developer. In this case the deviationsin shade owing to development fluctuations, as described above, do notarise. In the semi-wet development of this paper with the saidalkalinereacting phloroglucinol developers no favourable effect of thephosphate with regard to deviations in the shade of the azo dyestuffsowing to deviations in the concern tration and the application of thedevelopers is observed.

In order to avoid the disadvantageous consequences of developmentfluctuations in the semi-wet development of diazo film layers, it hasbeen proposed to sensitize diazo film layers with ap-diazo-dialkylaminobenzene compound in which every alkyl group containsat least 4 and at most 7 C-atoms and the two alkyl groups togethercontain 10, 11 or 12 C-atoms and at most one of the two alkyl groupscarries a side-chain at the cz-C-atom.

These diazo film layers contain very small quantities of the acidscommonly used in the diazotype process such as tartaric acid, citricacid, and alum. The diazo compounds are not suited for the sensitizationof some supports commonly used in the diazotype process, e.g. paper,because their solutions penetrate too far into them. They are aslo lesslight-sensitive than the diazo compounds which can be applied in thediazotype material according to the invention.

Diazotype materials which have been sensitized with actively couplingdiazo compounds, such as 4-diazo-2.5- dialkoxy-acylanilides,4-diazo-2.5-dialkoxy-aryl-mercaptd benzene compounds, and4-diazo-2.5-dialkoxy diphenyl compounds, and which are usually developedwith acid, strongly buffered developers, can be developed, as is known,according to the semi-wet process with alkalinereacting phloroglucinoldevelopers, and may then yield azo deystutf shades as pure or neutraland as dark as those obtained by development with the said stronglybuffered developers, if their light-sensitive layer contains a largequantity of a saturated aliphatic dicarboxylic acid, in which thecarboxyl groups are attached to carbon atoms which form part of asaturated hydrocarbon radical with at least 2 carbon atoms which may ormay not be branched and may or may not be provided with othersubstituents, the dissociation constants of said acid being smaller than1X Examples of such acids are succinic acid, glutaric acid and adipicacid. Using these acids, development fluctuations in the semi-wetdevelopment of the last-mentioned diazotype materials withalkaline-reacting phloroglucinol developers have considerably lessobjectionable consequences than airse when acids such as citric acid,tartaric acid, alum, and the like are employed.

The use of large quantities of aliphatic saturated dicarboxylic acids inthe light-sensitive layers of diazotype materials which have beensensitized wtih the same diazo compounds as those used in the diazotypematerials according to the invention, does result indeed in theformation of darker azo dyestufis in semi-wet development withalkaline-reacting phloroglucinol developers as mentioned above, and indecreased liability to development fluctuations, but both effects aresmaller than those which are obtained according to the presentinvention. Moreover, diazotype material according to the presentinvention has better keeping qualities.

In the diazo compounds which are used in the diazotype materialaccording to the invention it is not only the substituents in the phenylradical carrying the diazo group, but also the other groups besides thatphenyl radical which are attached to the tertiary nitrogen atom whichaffect the colour of the azo dyestuffs formed from the diazo compoundsby semi-wet development. In general the azo dyestuffs are darkeraccordingly as the tertiary nitrogen atom carries heavier groups. Thusmany diazo compounds of which the tertiary nitrogen atom carries twoethyl groups, when used in diazotype material according to the presentinvention, do not yield blackcoloured, but lighter, more or less brownto dark brown azo dyestuffs upon development of the diazotype materialwith phloroglucinol developer. Corresponding diazo compounds withheavier alkyl groups, e.g. n-butyl groups, or with an aralkyl group,e.g. a benzyl group, on the tertiary nitrogen atom often yield fineblack azo dyestufis. Such diazo compounds, however, are often lessreadily soluble in the sensitizing liquids which are used for themanufacture of the diazotype material according to the presentinvention, while their light-decomposition products often cause ratherserious discolouration of the diazotype copies. Both the said solubilityand the said discolouration are worse accordingly as the quantity ofphosphate used is larger.

Fine black azo dyestuffs, the colour of which remains practicallyunchanged when development fluctuations arise, are obtained withone-component diazotype material according to the present inventionwhich contains a p-diazo-2.5-dialkoxy phenylrnorpholine. The diazocompounds used in such onecomponent diazotype mate-rial do not have thedisadvantages which corresponding diazo compounds with heavier groups onthe tertiary nitrogen atom present.

One-component diazotype material sensitized with p- 6 diazo2.5-diethoxy-phenylmonpholine is known. It does not containorthophosphate.

The diazotype material according to the present invention may of coursealso contain mixtures of diazo compounds.

Furthermore it may contain the additives commonly used in one-componentdiazotype materials, such as stabilizers, e.g.naphthalene-1.3.-trisulphonic acid or one of its salts,anti-discolouration agents, e.g. thiourea, means for improving thesurface, eg. fine particles of silica, aluminium oxide, synthetic resinsor rice starch.

The diazo compounds used in the diazotype material according to thepresent invention can be prepared in several ways, erg. as described inBelgian Patent No. 564,343. Compounds with an aralkoxy group can beprepared from o-nitro-phenyl-aralkyl ethers in the manner described inthe said Belgian patent for the preparation of alkoxy compounds.Compounds with an aryloxy group can be prepared in a corresponding wayfrom o-nitro-diphenyl ethers.

The following examples will serve to illustrate the invention:

Example 1 White balse-paper of weight gm. as used for the diazotypeprocess is sensitized with a solution of:

13 g. of 4di-n-propylamino-3-ethoxybenzene diazonium chloride, zincchloride double salt 40 g. or primary sodium phosphate (2 'aq.)

2.5 g. of tartaric acid 1 g. of boric acid 20 g. ofnaphthalene-1.3.6trisulphonic acid sodium salt 30 cm. of polyvinylacetate dispersion Vinnapas H.60

in 1000 em. of water and dried.

The sensitized surface contains approximately 0.38 millimole of diazocompound per m? and a quantity of phosphate Which is the stoichiometricequivalent of 0.18 g. of P 0 per m. and has a ph 3.85.

The light-sensitive side of, a sheet of the diazotype paper thusprepared is covered with a sheet of tracing paper on which a pencildrawing has been made, and exposed in an exposure apparatus equippedwith actinically fluorescent low-pressure mercury vapour lamps. Exposureis continued until, in the portions which are in contact with the blankparts of the drawing, only a small quantity of diazo compound is left.

The moment at which the exposure has to be terminated can be determinedvery well by visual observation (from the direction of the light-source,for instance) of the change or colour which occurs in thelight-sensitive layer during the exposure. This moment is soon reached.

The latent diazotype copy thus obtained is developed by applying on itsimage surface a layer of approximately 8 g./-rn. of a developing liquidof the following composrtion:

31 g. of thiourea 15 g. of phloroiglucinol l g. of hydroquinonemonosulphonic aoid potassium salt 2 g. of dibutylnaphthalene sulphonicacid sodium salt (commercially available under the name or Sorbit P) 15g. of sorbitol 74 g. of potassium tetraborate (5 aq.)

12.6 g. of potassium hydroxide in 1000 cm. of water.

The developing liquid has a pH 9.8. The developed copy shows a strongblack positive image on a uniform foggy background.

If the developing liquid is diluted, erg. by addition of 200 em. ofwater, the copy developed with it shows an image which is less strongbut still black.

I If, instead of 40 g. of primary sodium phosphate, 12.5 g. of tartaricacid is used in the sensitizing liquid, a brownhlack image is obtainedwith the above-mentioned developer, and a greenish black, incompletelydeveloped, image with the diluted developer.

Example II White base-paper of weight 80 g./m. as used for the diazotypeprocess is sensitized with a solution of:

13.5 g. of 4-(N-methyl-N-benzyl)amino-3-methoxybenzene :diazoniumchloride, zinc chloride double salt 60 g. of primary sodium phosphate (2aq.)

3.5 g. of orthophosphoric acid 0.8 g. of methylcellulose in 1000 cm. ofwater and dried.

The sensitized surface contains approximately 0.38 millimole of diazocompound per m2 and a quantity of phosphate which is the stoichiometricequivalent of 0.29 g. of P per m. and has a pH 3.6.

A sheet of the diazotype paper thus prepared is imagewise exposed asdescribed in Example I. The moment at which the exposure has to beterminated can be observed very well and is soon reached.

The latent diazotype copy thus obtained is developed in a developingapparatus as described in Dutch Patent No. 67,009 at a speed of 5m./min., 8.5 g./m. of a developing liquid of the following compositionbeing applied:

31 g. of thiourea 6.5 g. of phloroglucinol 6.5 g. of resorcinol 2 g. ofisopropylnaphthalene sulphonic acid sodium salt 5 g. of sorbitol g. ofsaccharose 53 g. of potassium tetraborate (5 aq.)

9 g. of potassium hydroxide in 1000 cm. of water.

The developing liquid has a pH 9.4 A strong black image on a foggybackground is obtained.

When the developing speed in the above-menioned developing apparatus isdecreased to 3 m./ min., the quantity of developer applied is reduced to7 'g./m. A copy developed at that speed shows a somewhat weaker,incompletely developed image, the azo dyestufi? of which is somewhatgreenish black in colour.

If, instead of 60 g. of primary sodium phosphate, 12.5 g. of citric acidis used in the sensitizing liquid, development at a speed of 5 m./rnin.yields a dark brown image and development at a speed of 3 m./min. a veryincompletely developed green-brown image.

Example III White base-paper of weight 80 g./m. as used for thediazo-type process is pre-sensitized with about 10 g./m. of thefollowing liquid:

100 cm. of colloidal silica dispersion Satessa 14 2 g. of polyvinylalcohol, Rhodoviol BS 10 in 900 cm? of Water and dried.

The surface thus treated is sensitized with a solution of:

17 g. of 4-(N-2-hydroxyethyl-N-benzyl)amino-3-methoxybenzene diazoniurnchloride, zinc chloride double salt 40 g. of primary ammonium phosphate1.5 g. of tartaric acid 30 cm. of polyvinyl acetate dispersion, VinnapasH60 in 1000 GEL? of water and dried.

The sensitized surface contains approximately 0.5 millimole of diazocompound per rn. and a quantity of phosphate which is thestoichiornetric equivalent of 0.28 g. of P 0 per m. and has a pH 3.5.

A sheet of the diazotype paper thus prepared is imagewise exposed asdescribed in Example I. The moment g at which the exposure has to beterminated can be observed very well and is soon reached.

The latent diazotype copy thus obtained is developed by applyingapproximately 9 g./m. of the following developing liquid:

20 g. of sodium thiosulphate (5 aq.)

15 g. of thiourea 15 g. of phloroglucinol 1 g. of hydroquinonemonosulphonic acid potassium salt 2 g. of Sorbit P 2 g. of ethylenediamine tetraacetic acid, sodium salt 25 g. of sodium carbonate in 100cm. of Water.

The developing liquid has a pH 9.4. The developed copy shows a strongblack positive image on a foggy background, which does not showdeviations in shade due to vibrations and mechanical irregularities ofthe developing apparatus.

If, instead of 40 g. of primary ammonium phosphate, 27 g. of primaryammonium tartarate is used in the sensitizing liquid, considerabledifierences in azo dyestuil' shade due to vibrations and mechanicalirregularities of the developing apparatus are obtained, for example inthe form of alternating black and brown-black lines in the azo dyestuffimage.

Example IV White base-paper of weight g./rn. as used for the diazo-typeprocess is sensitized with a solution of:

14 g. of 4-[N-methyl N-(naphthyl-1)methyl]amino-3- methoxybenzenediazonium chloride, zinc chloride double salt 1 g. of aluminium sulphate(18 aq.)

30 cm. of polyvinyl acetate dispersion, Vinnapas H60 in 1000 cm. ofwater and dried.

On the light-sensitive surface a layer of approximately 10 g./rn. of thefollowing liquid is applied:

40 g. of primary sodium phosphate (2 aq.) 30 cm. of polyvinyl acetatedispersion, Vinnapas H.60 in 1000 cm. of water.

After drying, the light-sensitive surface contains approximately 0.55millimole of diazo compound per m and a quantity of phosphate which isthe stoichiometric equivalent or" 0.18 g. of P 0 per m. It has a pH 3.3.

A sheet of the diazotype paper thus prepared is image- Wise exposed asdescribed in Example I. The moment at which the exposure has to beterminated can be observed very well and is soon reached.

The latent diazotype copy thus obtained is developed by applyingapproximately 8.5 g./rn. of the following developing liquid:

10 g. of thiourea 15 g. of phloroglucinol 2 g. of Sorbit P 55 g. oftertiary sodium citrate (5 aq.) 4.2 g. of sodium hydroxide in 1000 cm.of water.

The developing liquid has a pH 9. The developed copy shows a strongblack positive image on a foggy background.

When the concentration of the components of this developer hasincreased, for example in consequence of evaporation of the developer inthe developing apparatus, to such an extent that the original volume of1030 cm. has decreased to about 750* cm. the development of a copy onthis light-sensitive material in an otherwise similar fashion results inan image of which the azo dyestuff has practically the same colour asthat which is obtained with the developer of the normal concentration.

If, instead of 40 g. of primary sodium phosphate, 6 g. of aluminiumsulphate (18 aq.) is used in the liquid applied on the light-sensitivesurface, a copy developed with the above-mentioned developer of thenormal concentration shows a strong black image, but a copy developedwith the developer after evaporation to 750 cm. shows a brown-violetinstead of a black image.

Example V White base-paper of weight 80 g./m. as used for the diazo-typeprocess is sensitized with a solution of:

11 g. of 4-dimethylamino-3-phenoxybenzene diazonium chloride, zincchloride double salt 50 g. of primary potassium phosphate 1.2 g. oforthophosphoric acid 0.8 g. of methylcellulose in 1000 cm? of water anddried.

The sensitized surface contains approximately 0.5 millimole of diazocompound per m? and a quantity of phosphate which is the stoichiometricequivalent of 0.41 g. of P per m. and has a pH 3.5.

A sheet of the diazotype paper thus prepared is imagewise exposed asdescribed in Example I. The moment at which the exposure has to beterminated can be observed very well and is soon reached.

The latent diazotype copy thus obtained is developed as described inExample II.

The developed copy shows a grey-black positive image on a foggybackground and shows only small variation of shade due to developmentfluctuations.

If, instead of 50 g. of primary potassium phosphate, 15 g. of aluminiumsulphate (18 aq.) is used in the sensitizing liquid, considerabledifferences in azo dyestuff shade due to development fluctuations areobtained.

Example VI A cellulose acetate layer of weight approximately 20 g./m.applied on natural tracing paper of weight approximately 80 g./m. issuperficially hydrolyzed to a depth of approximately 4 1. and, afterremoval of the chemicals used for the hydrolysis by washing with water,is sensitized with a solution of 1 24 g. of4-dimethylamino-3-p-chlorophenoxy-6-chlorobenzene diazonium chloride,zinc chloride double salt 80 g. of primary sodium phosphate (2 aq.)

1.2 g. of orthophosphoric acid 100 cm. of ethanol 96% in 900 cm. ofwater and dried.

The light-sensitive hydrolyzed layer contains approximately 0.75millimole of diazo compound per m. and a quantity of phosphate which isthe stoichiometric equivalent of 0.46 g. of P 0 per m. and has a surfacepH 3.2.

A sheet of the diazotype material thus prepared is image-wise exposed asdescribed in Example I. The moment at which the exposure has to beterminated can be observed very well and is soon reached.

The latent diazotype copy thus obtained is developed by applyingapproximately 8 g./m. of the following developing liquid:

53 g. of sodium thiosulphate (5 aq.)

20 g. of thiourea 8 g. of borax 7 g. of phlorogucinol 7 g. of resorcinol1 g. of hydroquinone monosulphonic acid potassium salt 2.5 g. of SorbitP 1.5 g. of ethylene-diamine tetraacetic acid, sodium salt 27.5 g. ofsodium carbonate in 1000 cm. of water.

The developing liquid has a pH 9.4. The developed copy shows abrown-black image on a foggy background which shows little variation ofshade due to development fluctuations.

If, instead of g. of primary sodium phosphate, 19 g. of citric acid isused in the sensitizing liquid, considerable differences in azo dyestuifshade due to development fluctuations are obtained.

The copy produced according to this example can be used as anintermediate original for making further copies on diazotype paper.

Example VII A baryta-coated paper of weight g./m. is sensitized with asolution of:

20 g. of 4-dimethylamino-3-benzyloxybenzene diazonium chloride, zincchloride double salt 56 g. of orthophosphoric acid, 50% by weight 52.7g. of tertiary sodium orthophosphate (12 aq.)

2.5 g. of gum arabic 30 cm. of polyvinyl acetate dispersion, VinnapasH60 in 1000 cm. of water and dried.

The sensitized surface contains approximately 0.7 millimole of diazocompound per m. and a quantity of phosphate which is the stoichiometricequivalent of 0.38 g. of P 0 per m. and has a pH 4.3.

A sheet of the diazotype paper thus prepared is imagewise exposed asdescribed in Example I. The moment at which the exposure has to beterminated can be observed very well and is soon reached.

The latent diazotype copy thus obtained is developed as described inExample II. The developed copy shows a grey-black positive image on agrey foggy background, which shows little or no deviation in shade dueto vibrations and mechanical irregularities of the developing apparatus.

If, instead of the above-mentioned quantity of orthophosphoric acid andtertiary sodium orthophosphate, 16 g. of tartaric acid is used in thesensitizing liquid, the copy shows an image with considerabledilferences in azo dyestuff shade due to vibrations and mechanicalirregularities of the developing apparatus, in the form of alternatingbrown and grey-black lines.

Example VIII White base-paper of weight 80 g./m. as used for thediazotype process is sensitized with a solution of:

12.5 g. of 4-(N-methyl-N-benzyl)amino-3-methoxy 6- bromobenzenediazonium chloride, zinc chloride double salt 70 g. of primary sodiumorthophosphate (2 aq.)

1.2 g. of orthophosphoric acid 20 cm. of polyvinyl acetate dispersion,Vinnapas H.60

in 1000 cm. of water and dried.

The sensitized surface contains approximately 0.5 millimole of diazocompound per 111. and a quantity of phosphate which is thestoichiometric equivalent of 0.56 g. of P 0 per m. and has a pH 3.5.

A sheet of the diazotype paper thus prepared is imagewise exposed asdescribed in Example I. The moment at which the exposure has to beterminated can be observed very Well and is soon reached.

The latent diazotype copy thus obtained is developed as described inExample VI. The developed copy shows a grey-black positive image on aviolet-grey foggy background, which shows little or no deviation inshade due to vibrations and mechanical irregularities of the developingapparatus.

If, instead of 70 g. of primary sodium orthophosphate, 22 g. of citricacid is used in the sensitizing liquid, the copy shows a dark-brownimage on a red-brown foggy background with considerable differences inazo dyestulf shade due to vibrations and mechanical irregularities ofthe developing apparatus, for example in the form of alternatinggreen-brown, dark-brown and red brown lines.

1 1 Example IX White base-paper of Weight 80 g./m. as used for thediazotype process is sensitized with a solution of:

24 g. of 4-morpholino-2,S-di-n-propoxybenzene diazonium chloride, zincchloride double salt 60 g. of primary sodium orthophosphate (2 aq.)

3.5 g. of orthophosphoric acid 20 cm. of polyvinyl acetate dispersion,Vinnapas H60 in 1000 cm. of water and dried.

The sensitized surface contains approximately 0.45 millimole of diazocompound per m? and a quantity of phosphate which is the stoichiometricequivalent of 0.23 g. of P per m2, and has a pH 3.4.

A sheet of the diazotype paper thus prepared is imagewise exposed asdescribed in Example I. The moment at which the exposure has to beterminated can be observed very well and is soon reached.

The latent diazotype copy thus obtained is developed as described inExample II. The developed copy shows a strong black positive image on afoggy background which shows little variation of shade due todevelopment fluctuations.

If, instead of 60 g. of primary sodium orthophosphate, 13 g. of citricacid is used in the sensitizing liquid, a dark violet-brown image isobtained.

Example X \Vhite base-paper of weight 80 g./m. as used for the diazotypeprocess is sensitized with a solution of:

14 g. of 4-morpholino-2,S-di-n-propoxybenzene diazonium chloride, zincchloride double salt 20 g. of secondary sodium orthophosphate (2 aq.)

40 g. of primary sodium orthophosphate (2 aq.)

2 g. of citric acid 20 g. of naphthalene-1.3.6-trisulphonic acid, sodiumsalt 20 cm. of polyvinyl acetate dispersion, Vinnapas 1-1.60

in 1000* cm. of water and dried.

The sensitized surface contains approximately 0.45 millimole of diazocompound per m. and a quantity of phosphate which is the stoichiometricequivalent of 0135 g. of P 0 per m. and has a pH 5.4.

A sheet of the diazotype paper thus prepared is imagewise exposed asdescribed in Example I. The moment at which the exposure has to beterminated can be observed very well and is soon reached.

The latent diazotype copy thus obtained is developed as described inExample H. The developed copy shows a strong black positive image on afoggy background which shows little variation of shade due todevelopment fluctuations.

If, instead of 20 g. of secondary sodium orthophosphate and g. ofprimary sodium orthophosphate, g. of tertiary sodium citrate and 15 g.of citric acid are used in the sensitizing liquid, considerabledifierences in azo dyesturT shade due to development fluctuations areobtained.

We claim:

1. One-component diazotype material comprising a support carrying alight-sentive layer containing a lightsensitive diazo compound in theabsence of an azo coupling component, said light-sensitive layer havingan acid reaction and said diazo compound being a p-amino ben zenediazonium salt which has a greater coupling activity than p-diazo ethylbenzylaniline, which is derived from a tertiary amine with only one arylradical attached directly to the tertiary nitrogen atom, and whichcarries in the 4-position the diazo group, in the 2-position a memberselected from the class consisting of alkoxy, aryloxy and aralkoxygroups, and in the 5-position a member selected from the classconsisting of a hydrogen atom, a halogen atom, a methyl group and analkoxy group, the said lightsensitive layer containing a quantity oforthophosphate selected from the class consisting of alkali metal andammonium orthophosphates in the amount of the stoichiometric equivalentof at least 0.15 g. and at most 0.9 g. of P 0 per square meter of saidmaterial.

2. One-component diazotype material according to claim 1, wherein thelight-sensitive layer contains a diazonium salt of ap-diazo-2,5-dialkoxy-phenylmorpholine.

3. A process for the production of a diazotype print which comprisesimagewise exposing a diazotype material as defined in claim 1 anddeveloping the exposed material by the semi-Wet method using a developercontaining phloroglucinol.

4. One-component diazotype material according to claim 1, said diazoniumsalt being a diazonium salt of 4- di-n-propylamino-3-ethoxybenzene.

5. One-component diazotype material according to claim 1, said diazoniumsalt being a diazonium salt of 4-dimethylamino 3 p-chlorophenoxy 6chlorobenzene.

6. One-component diazotaype material according to claim 1, saiddiazonium salt being a diazonium salt of4-morpholino-2,S-di-n-propoxybenzene.

References Cited in the file of this patent UNITED STATES PATENTS2,217,189 Sus Oct. 8, 1940 2,405,523 Sease et al. Aug. 6, 1946 FOREIGNPATENTS 476,718 Canada Sept. 4, 1951

1. ONE-COMPONENT DIAZOTYPE MATERIAL COMPRISING A SUPPORT CARRYING ALIGHT-SENSITIVE LAYER CONTAINING A LIGHTSENSITIVE DIAZO COMPOUND IN THEABSENCE OF AN AZO COUPLING COMPONENT, SAID LIGHT-SENSITIVE LAYER HAVINGAN ACID REACTION AND SAID DIAZO COMPOUND BEING A P-AMINO BENZENEDIAZONIUM SALT WHICH HAS A GREATER COUPLING ACTIVITY THAN P-DIAZO ETHYLBENZYLANILINE, WHICH IS DERIVED FROM A TERTIARY AMINE WITH ONLY ONE ARYLRADICAL ATTACHED DIRECTLY TO THE TERTIARY NITROGEN ATOM, AND WHICHCARRIES IN THE 4-POSITION THE DIAZO GROUP, IN THE 2-POSITION A MEMBERSELECTED FROM THE CLASS CONSISTING OF ALKOXY, ARYLOXY AND ARALKOXYGROUPS, AND IN THE 5-POSITION A MEMBER SELECTED FROM THE CLASSCONSISTING OF ALKXY, ARYLOXY AND ARALKOXY GROUPS, AND IN THE 5-POSITIONA MEMBER SELECTED FROM THE CLASS CONSISTING OF A HYDROGEN ATOM, AHALOGEN ATOM, A METHYL GROUP AND AN ALKOXY GROUP, THE SAIDLIGHTSENSITIVE LAYER CONTAINING A QUANTITY OIF ORTHOPHOSPHATE SELECTEDFROM THE CLASS CONSISTING OF ALKALI METAL AND AMMONIUM ORTHOPHOSPHATESIN THE AMOUNT OF THE STOICHIOMETRIC EQUIVALENT OF AT LEAST 0.15 G. ANDAT MOST 0.9 G. OF P2O5 PER SQUARE METER OF SAID MATERIAL.